Police in Vancouver are looking for a serial rapist responsible for as many as eight attacks after DNA evidence linked an unknown man to a series of assaults in the city.

Investigators believe that the suspect is responsible for at least three late-night attacks on women returning home from the downtown entertainment district. The attacks date back to the summer of 2009, and all of the victims were under the age of 30.

"The suspect has targeted women who are temporarily isolated, late at night and when few if any witnesses are around," Sgt. Matt Clarke told reporters.

"This male is a predator. He's targeting these women and he's taking an opportunity to attack when they're in a vulnerable position."

He added that the suspect may be linked to five more sexual assaults in Vancouver, and investigators are now looking for connections.

The DNA samples taken from the crime scenes do not match anyone in the police database, Clarke said.

Police believe the suspect either follows victims away from downtown until they reach more secluded neighbourhoods, or waits in residential areas for revellers to return home.

The suspect is described as tanned or olive-skinned and of medium height, with dark hair and an average build. He is believed to be in his 20s or 30s and is said to be well groomed and dressed.

Police have released surveillance footage of a suspect on Thursday, and Clarke say investigators "strongly believe" the man depicted is responsible for the assaults.

The first attack happened shortly after 4 a.m. on Canada Day in 2009, when a woman was attacked in the 1600-block of West 4th Avenue near the Granville Street Bridge.

The next woman was assaulted in the 900-block of Beach Avenue on Nov. 15, 2009, and the most recent attack took place on June 12 near the intersection of Marinaside Crescent and Drake Street.

Police say that all of the victims were emotionally traumatized, and one of the women suffered scrapes and bruises when she was thrown to the ground.

Investigators say the suspect could be responsible for more attacks, and are asking anyone with information to call Vancouver police.

This wouldn't the first time Vancouver police have used DNA evidence to identify a serial rapist.

Last month, former political campaigner Ibata Noric Hexamer was charged in four violent sexual assaults against girls as young as six over a 15-year period.

The former administrator with the municipal COPE party was identified after DNA evidence linked him to crime scenes where girls were raped at knifepoint.